Good to see you back to work!
I think core loop is essential and if you have time to read, I have some postmortem for Infiltration here
Essentialy, this kind of games need for sure a core loop, but more important need to be part of a coherent vision. Priority, priority, priority! Don't add new systems until base systems are working and game receive good feedback from players
Thanks for the link, I've read it and found it pretty interesting. I played the game itself, but never saw this post about it.
You're right that we need to ensure that the core element of the game is concrete and functional before expanding. I'd say that is the political system, and the player's interactions with it.
We've done a vast amount of stability testing for the system itself, to see if the AI is able to respond correctly to threats (identifying dark agents and removing them before the shadow spreads too far by itself), and to converge towards a semi-stable map state (no giant blob nations, but still unifying together).
Now we need to expand the options a little bit, then do a vast amount of testing of the player's actions (make sure no action is overpowered or underpowered) and general UI polish.
